Don’t Eat the Cookie Dough! Raw Cookies Linked to E. coli Outbreak


Home / Don’t Eat the Cookie Dough! Raw Cookies Linked to E. coli Outbreak

Wait until the cookies are baked, to avoid E. coli: Image by garytamin

Is raw cookie dough bad for you? E. coli has been linked to a variety of contaminated foods such as fresh produce, ground beef, unpasteurized milk or cheese, and untreated water, but uncooked pre-packaged cookie dough may be added to the list. In research published December 09, 2011, scientists investigated a multi-state outbreak of E. coli O157:H7, in which patients became sick after eating this type of raw cookie dough.

Escherichia Coli (E. Coli) Bacteria Dangers

Escherichia coli (E. coli) is a large, mostly harmless, group of bacteria. There are some types of E. coli, however that produce a toxin called Shiga toxin, which can make you very sick. E. coli that produces the Shiga toxin is called E. coli O157:H7, or STEC for short. You can get sick when consuming food or water that has been contaminated with STEC. According to the Centers for Disease Control and Prevention (CDC), five to ten percent of people with STEC develop a potentially-fatal complication called hemolytic uremic syndrome (HUS) which occurs when the kidneys begin to shut down.

E. coli Outbreak of 2009

E. coli makes some raw, unpasteurized foods dangerous. Photo by: Mattosaurus

In this study, researchers studied the outbreak of E. coli O157:H7 in 77 patients in 30 states who become ill between March 16 and July 8, 2009. Thirty-five of these patients were hospitalized, and ten developed HUS. Thirty-three of the patients ate ready-to-bake commercial prepackaged cookie dough prior to their illness. All ingredients of the cookie dough were tested for possible E. coli contamination. The eggs that were used were pasteurized, making them an unlikely source of E. coli. Molasses, sugar, baking soda, and margarine all undergo pathogen-kill steps to eliminate E. coli and other bacteria. The flour that was used in making the cookie dough is a raw product, meaning that it does not undergo pathogen kill steps. Even though there is no conclusive evidence that flour was the cause of the E.colioutbreak, it still remains a suspect.

Decoded Science asked Dr. Karen Neil, CDC Medical Epidemiologist and lead author for the study, what recommendations she has for the manufacturers of the prepackaged ready-to-bake cookie dough.

The authors (Gwen Biggerstaff, Kathryn MacDonald, Eija Trees, Carlota Medus, Kimberlee Musser, Steven Stroika, Don Zink, Mark Sotir) recommend that all manufacturers should consider formulating ready-to-bake commercial prepackaged cookie dough to be as safe as a ready-to-eat food item.”

According to the study, companies should consider using heat-treated flour to kill any lingering bacteria for ready-to-bake cookie dough.

Food Safety and E. Coli

Prepackaged ready-to-bake cookie dough may not be safe to eat before baking. Photo by: cyclonebill

Outbreaks such as the E. coli outbreak of 2009 are a good reminder for everyone to practice safe food handling when preparing, cooking, and storing food. Decoded Science asked Dr. Neil what her recommendations are, in light of this research. She suggests, “Do not eat unbaked cookie dough or similar products that are intended to be cooked or baked before consumption.”
This is the first reported outbreak of STEC associated with eating prepackaged ready-to-bake cookie dough. More extensive and effective education is needed to inform consumers about the risks associated with eating raw pre-packaged cookies, according to the authors of the study.


Centers for Disease Control and Prevention. Escherichia coli O157:H7 and other Shiga toxin-producing Escherichia coli (STEC). Accessed on December 10, 2011.

Neil, K., Biggerstaff, G., MacDonald, K., Trees, E., Medus, C., Musser, K., Stroika, S., Zink, D.,  Sotir, M. A Novel Vehicle for Transmission of Escherichia coli 0157:H7 to Humans: Multistate Outbreak of E. coli O157:H7 Infections Associated With Consumption of Ready-to-Bake Commercial Prepackaged Cookie Dough. (2011). Clinical Infectious Diseases. Accessed December 10, 2011.

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